As concern for the environment increases, regulations for preventing the escape of volatile hydrocarbon vapors to the atmosphere are being promulgated by governmental agencies. One source of hydrocarbon vapors is the fuel tanks of vehicles using gasoline or other hydrocarbon fuels of high volatility. With current automotive fuel tank designs, fuel vapor can escape during the filling of the tanks and usually even after the tank is filled.
The use of an on-board vapor storage container to remove excess fuel vapor from the fuel tank is one solution to this problem. Some of these devices use a high capacity or high flow rate valve to control the flow of vapor from the fuel tank to a vapor storage canister. From the storage canister, the vapor may be fed into the intake manifold of the engine to be consumed by the engine.
Current on-board vapor recovery systems send essentially all the vapor removed from the fuel tank to the vapor canister. This can produce a high flow rate of fuel vapor to the vapor canister requiring a large vapor canister which increases the cost of the vapor recovery system.